Vol. 10, Issue 9, Part A (2024)

Oil and Gas accumulations located in the porous spaces of the formation exist as a single hydraulically connected system. During the life of an oil field the production tends to pass through a number of stages, based on this it is very important to know as much about types of flow systems in reservoir rock in order to use the appropriate model to describe the relationship between the pressure and flow rate. Types of reservoir fluids with their representative equations and the combination of the three equations; the equation of continuity, the equation of motion and the equation of state treated not only in the physical concept but also in the mathematical one step by step deriving the basic equations applicable to each of the types of fluids in the steady state and in isotropic porous media, are the object of this paper.